A method for operating a user equipment (UE) for channel state information (CSI) feedback in a wireless communication system comprises receiving, from a base station (BS), CSI feedback configuration information including two parameters (p0, p1) for determining a set of M basis vectors, the first parameter (p0) is for a first rank set and the second parameter (p1) is for a second rank set; generating a CSI feedback based on the CSI feedback configuration information, the CSI feedback generated for a rank value v from one of the first and second rank sets and the CSI feedback includes the set of M basis vectors, M is determined based on the (p0) if the rank value v belongs to the first rank set and based on the (p1) if the rank value v belongs to the second rank set; and transmitting, to the BS, the CSI feedback over an uplink channel.